1. Field of the Invention
The present invention typically relates to a fuel supply apparatus of an internal combustion engine in a motorcycle and the like in which a parallel multicylinder engine is mounted.
2. Description of the Related Art
In an engine with a large lateral width such as a parallel four-cylinder engine or the like in a motorcycle, a throttle body, a secondary injector and an air cleaner and so on surrounding them, which are arranged at an upper part of the engine, also become large in lateral width to increase the lateral width of a vehicle frame. However, a portion of the vehicle frame large in lateral width is a portion corresponding to the elbows and the knees of a rider and therefore decreases the degree of freedom at riding of the rider and deteriorates the aerodynamic performance due to the large lateral width.
For example, Patent Document 1 discloses an intake apparatus in which the width of a vaporizer unit is decreased to decrease the vehicle frame width. In this intake apparatus, the path from an intake valve of the engine to a throttle body is tilted so as to make the pitch width between throttle bodies smaller than the pitch between cylinders, thereby decreasing the vehicle frame width (Patent Document 1, FIG. 17 and so on).
[Patent Document 1] Japanese Laid-open Patent Publication No. 10-077908
However, in the conventional apparatus as described above, a certain distance is required to gradually tilt the path from the intake valve of the engine to the throttle body. Therefore, the distance from the intake valve to the throttle body becomes longer to cause a decrease in response (accelerator response) of the engine. Further, the intake path is tilted at a position where the flow velocity is increased after the throttle body (on the intake downstream side) and thereby causes a problem such as a decrease in engine output and so on.